<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>黑白拖拽转换</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        #box{
            width: 1200px;
            height: 675px;
            margin: 80px auto;
            background-image: url("img/img-original.jpg");
            position: relative;
        }
        #cover{
            width: 600px;
            height: 675px;
            position: relative;
            background-image: url("img/img-modified.jpg");
        }
        #button{
            width: 50px;
            height: 50px;
            border-radius: 25px;
            background-color: red;
            position: absolute;
            left: 575px;
            top: 312.5px;
        }
    </style>
</head>
<body>
<div id="box">
    <div id="cover"></div>
    <div id="button"></div>
    <span>左文本</span><span>右文本</span>
</div>
<script>

</script>
</body>
</html>